Breathing indicator



Jan. 27, 1948. H. w. LINDSAY 2,435,181

BREATHING :[NIDICATOHA Filed D60. .18, 1945 ,foxYdE/v SWPU L//YE 1N VEN TOR.

Patented Jan. 27, 1948 BREATHING INDICATOR Harold W. Lindsay, Redwood City, Calif., assignor to the United States of America, as represented by the Secretary of War Application December 18, 1945, Serial No. 635,741

' 4 Claims. (Cl. 177-311) The invention described herein may be manufactured and used by or for the Government c-f the United States for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to breathing indicators or apparatus which will give some indication at a remote point that a member of the crew of a bomber or other large aircraft in flight is ceasing to breathe through his oxygen mask. On numerous occasions during the present war, personnel in aircraft have died of anoxia or an oxemia or for other causes, without knowledge of the other members of the crew that they were in distress. A breathing indicator may save many lives as effectual measures usually may be taken to restore respiration, provided the other members of the crew are apprised of the danger in suicient time. Y

One of the objects of the invention is to provide apparatus which will give a danger signal whenever the supply pressure of the oxygen drops, whether from failure of the supply itself or by disconnection of the oxygen mask. The invention further aims to provide a breathing indicator which is of simple construction, which is'light in weight, occupies little space, is easily installed and maintained, requires little power, is dependable, and is readily adaptable for use with oxygen equipment already standardized for military and naval service. Other objects Iwill be apparent from the following description of a preferred embodiment of the invention shown in the accompanying drawing, in which the single figure shows diagrammatically an arrangement of parts for indicating at a remote point breathing and cessation of breathing.

Referring particularly to the drawing, an oxygen mask I is connected by tubing 2 and a quick-detachable coupling 2a to a standard oxygen demand regulator 3 which in turn is connected by tubing 4 to the oxygen supply line 5. A bellows 6, which may be similar to a Sylphon bellows, is also coupled at one end to the oxygen demand regulator 3 and is so constructed and arranged that it collapses under atmospheric pressure with each breath inhaled, while with each exhalation it expands, due in part to the counterpressure of the exhalation and in part to the action of an internal spring, not shown. An insulating link 8 is secured at one end to bellows 6 and is pivotally connected at its opposite end with a switch 9 to control circuits which will now be described.

To indicate that the apparatus is functioning,

an electric lamp IIl is in a circuit including leads II, I2, I3, and I4, a battery or other current source I5 and the contacts I6 and I1 which the switch 9 short circuits when in closed position. Obviously, if the bellows is moved suciently, switch 9 will close the circuit with each exhalation and open it with each inhalation, thus causing signal lamp I0 to light up and go out at corresponding times. Lamp IU may of course be replaced by some other visual indicator emitting no light rays, in the event that the conditions of the flight necessitate a darkened aircraft, or it may be replaced with an aural indicator. f'

Also connected to battery I5 is a circuit including lead I3, a conductor I8, heating coil i9 and a lead 20 which is connected with lead II between lamp I8 (or other indicator) and switch terminal Il. With this arrangement, coil I9 will carry current whenever the lamp circuit is closed by switch 9, and thus the coil will be heated intermittently. A bimetallic arm 2I, which is`one half of a switch 22, is provided with a contact 23 on one end. A conductor 24 connects the bimetallic arm 2I with lead I3, so that current from the battery is conducted through arm 2l to contact 23. A second bimetallic arm 25, forming the other half of switch 22, has a contact 26 on one end, said contact co-operating with contact 23 to close a circuit under certain conditions which will be described. A lead 21 is electrically connected with the second bimetallic arm 25 and is coupled to an electric warning or danger lamp 28 which may be a red bulb or be behind a red light-transmitting panel, not shown. A lead 29 couples the other contact of lamp 28 with the lead I4 on the negative side of the battery. An aural signal may be operated instead of or in conjunction with lamp 28. The signal lamps Ill and 28 may be located at a central station in the airplane, in the pilots compartment, or wherever convenient.

It will be understood that the described arrangement, which is for a single person, will be duplicated for each member of the aircraft crew.

Operation As long as normal or rhythmic breathing continues, the bellows-operated switch 9 will close and open, thus heating the bimetallic strip 2| intermittently to maintain its average temperature suiiiciently high to sustain an air gap or open circuit between the contacts 23, 26, which will keep the danger lamp 28 dark. However, if respiration weakens, or if the supply pressure drops or if the oxygen mask is disconnected, the

bellows may not close switch 9, and if switch 9 stays open more than a predetermined time interval, which may be seconds, 30 seconds or any other desired time interval, heating coil I9 will cool to a point where the bimetallic strip 2| will curl toward strip 25, to bring contacts 23 and 26 together, to close the circuit of the danger lamp 28. The pilot or other lperson at the central station will then give the necessary warning to other crew members over the interphone.

Obviously, the bellows must be so constructed as to operate well at all temperatures .and at.- mospheric pressures which may be encountered in a night. Also, switch 22 Should be shielded and insulated so as to be protected against .ine jury and rendered insensitive to sudden and sharp temperature variations. The second vvbimetallic strip 25 is provided to compensate for changes in ambient temperature, or in other words, to maintain the air gap between contacts 23 and 26 fairly constanteven thoughswitch `l22 is subjected `to temperature Changes of 100 or more, and it may be made manually adjustable (not shown) vto vary said air gap and may be shielded (not shown) by insulation from the heat of coil vlil. A master switch (not shown) may also be employed to keep all circuits open until the oxygen mask is adjusted and regular breathing through the oxygen demand regulator is established. While the ,apparatus` is described as though it were exclusively for use with oxygen, obviously it -will operate with any combination of breathable gases. Various changes in the apparatus willoccur to those skilled in the art fand Iadoonot wish lto be limited to the particular arrangement shown,-except .as .required by the appended claims.

yWhitt V I Claim ,iS

-1- 1.11 an oxygen Warning system of the charaoter described, in combination, an oxygen supply source; ,an oxygen mask; a conduit connecting the .oxygen mask with the source of supply; a pressure-responsive switch operatively associated withsaid conduit and opening and closing responsive to variations in pressure due to consumption maldevicewhich is continually being heated upon 1 closing of Asaid switch; and connections between thethermal device .and the warning indicator so constructed :and arranged that cooling of the thermal device below a certain predetermined temperature will cause the indicator to show or Sound a wor-lling.

12. In combination with an oxygen supply system including a source of supply, an oxygen demand regulator connected with the source of supe ply, and `an oxygen mask connected with the oxygen demand regulator; a bellows connected with the oxygen demand regulator and so constructed and arranged that with every breath inhaled and exhaled by the person wearing the mask, thebcllows contracts and expands; a circuit including a source of power, leads and a switch connected with the leads; means mechanically connecting the :bellows with the switch so that movements of the bellows responsive to normal breathing of said :person will close and open said switch; signaling means operated by each closing ofk said circuit; a second normally open circuit; a thermostatic switch connected to the first circuit to be energized thereby and constructed and arranged to automatically couple the second circuit to the source of power when the current of the first circuit fails for a predetermined period; and a warning signal coupled into the 4second circuit to give an indication at a remote point of weak breathing or cessation of breathing of the person `wearing the mask.

,3. In combination with an oxygen system including a source of supply, an oxygen demand regulator connected to the source of supply, and .an oxygen mask connected with the oxygen demand regulator; a .device movable responsive to atmospheric pressure made effective by inhalation by the person wearing the oxygen mask, and movable oppositely responsive in part to counterpressure from the exhaling lungs of said person; a switch mechanically connected to said device; a circuit connected -with a source of electricity and said switch, and being so connected and lil.- ranged that the switch closes and opens it each time the device moves through one cycle respon-f sive to the normal breathing of said person; a thermal-,responsive switch which is a part of said circuit and is heated electrically whenever -Said circuit is closed by the rst-named switch; a lsccond circuit which is automatically connected to the source of power by the thermal switch when thelatter cools responsive to opening of the rstnamed circuit; and an electricalindicating device which is connected in the second circuit and is energized when the second circuit is closed..

4, In combination with an oxygen supply sys-V tern including a :source ofoxygen supply, 4arr-oxyeen demand regulator connected to the source 'of supply, and an oxygen mask connected with .the oxygen demand regulator; a bellows connected with the oxygen demand regulator and so oonstructed and arranged that with every breath inhaled and exhaled by the kperson wearing ,the oxygen mask, the bellows contracts and expands; a circuit including a source of power, -a switch and leads; means mechanically connecting the bellows with the switch, theparts being so ,constructed and arranged that movements of the bellows responsive to normal breathing will close and open said switch; a second normally open circuit including signaling means; and a device which oportunas upon failure of energization of the first-named circuit after a predetermined period to connect the second circuit with a source of power tocause the vsignaling means to kgive warning of the open circuit condition of the first circuit, and hence to warn .of weak breathing ,or cessation of breathing,

HAROLD W. LINDSAY- REFERENCES yCITED vThe following references are of record .in the le of this patent:

UNITED STATES PATENTS Number Name Date 51,134,320 Drew Apr. 6, 1915 V.2,087,598 Hebler July 20, v193'7 2,193,945 Strauss et al. Mar. AV19, 1940 324,424 APollack July 13, 1943 

